BMW Knowledge Base

BMW 3 Series G20/G21 (2019–Present): Generation Overview

The BMW G20 is the seventh generation of the 3 Series and has been on the market since spring 2019; the Touring (G21) followed in fall 2019. With the G20, BMW moved entirely to the modular B47/B48/B57/B58 engine family. The line is technically more mature than the F30 predecessor, but new topics come to the fore.

BMW E39: Why the Airbag Light Is On and How to Fix It for 3 Euros

Find out why the airbag light comes on in your BMW E39 and how to fix the problem for 3 euros. Diagnostics, contact cleaning, prevention—a step-by-step guide for owners.

The Complete BMW E36 Reliability Guide: Weak Spots and Prevention

The complete BMW E36 reliability guide: weak spots in the cooling system, engine, suspension, and electronics. Prevention tips and a buyer's checklist.

How the System Works

Why the KGE membrane on the N52, N54, N55, and B58 typically tears, what symptoms appear, and how the repair is done.

The BMW N47 Engine: Timing Chain Problems and Repair — A Complete Owner’s Guide

A complete guide to the BMW N47 engine: timing chain problems, failure symptoms, what happens when the chain snaps, prevention, and replacement. Practical advice for BMW owners.

BMW Water Pump—Electric Pump Life and Replacement Cost

Electric water pumps from N52 to B58: typical failure patterns, fault codes, and honest shop costs.

Buying Guide: Is a Pre-Purchase Inspection Worth It for a BMW X7 G07 xDrive40i?

Step-by-Step Check

The classic failure: the FRM3 loses its coding, and the turn signals and lights stop working.

How the System Works

Diagnostics for NOx sensors, the SCR catalyst, the AdBlue dosing valve and the tank heater, including unlock and adaptation procedures.